Swimming pool



March 11, 1958 v J. PRUDEK 2,825,910

` SWIMMNG Pool.

' 3 Sheets-Sheet 2 Filed Aug. 30. 1954 JACK PRL/05K v INVENTO/P HUEBNER, @Eef/LER,

WORREL 8 HERZ/6 TTORNEVS SWIMMING POOL Jack Prudek, Fresno, Calif.

Application August 30, 1954, Serial No. 452,979

13 Claims. (Cl. 4`172) The present invention relates to swimming pools and more particularly to 'a combined swimming pool and appartenant equipment therefor conducive to improved safety.

lt is becoming increasingly popular to build or otherwise install swimming pools in domestic areas. However, several factors have prevented or deterred many people from owning their own pools. Probably of greatest significance in this regard has been the abnormally high cost of the average cement pools permitting acquisition only by those of some means. Although there are presently in use several types of inflatable pools purchasable at relatively low cost, these have been subject to certain difficulties impairing their full and widespread acceptance.

A major deterring factor in all types of pools has been the hazards of their presence, whether or not in use. Especially is this true of pools in private yards where inadequate fencing and inability to maintain constant watch make the pool area a danger zone, particularly for animais and children. The tragedies in this connection have been numerous and widely publicized.

Even when pools are properly protected by fences to prevent accidental drownings, there are additional hazards during actual use of the pool. Most pools are constructed with a graded depth permitting diving at one end and wading at the opposite end. Many children, and especially those unable, or just learning, to swim, cannot stand with their heads above water even in the shallow or wading sections of the pool. When the water is suflciently shallow, children may intentionally or accidentally wander into deeper areas with fatal consequences. This not only adds to the hazards of a pool but greatly reduces the swimming enjoyment of those in charge of the children who must exert constant diligence.

The essence of this invention is the provision of a swimming pool of low cost construction which is designed with safety as a prime consideration.

An object of this invention is to provide a swimming pool having improved safety features.

Another object is to provide a swimming pool with a submersible cover adapted to cover the pool when not in use and to rest on the bottom of the poolwhen in use.

Another object is to provide a swimming pool with a removable partition between the shallow and deep ends thereof.

Another object is to provide a swimming pool with a wading section partitioned off from the rest of the pool and having a variable depth.

Another object is to provide a .swimming pool incorporating a sectioned foraminous net, screen or other member adapted to cover the entire pool or to rest on the bottom of the pool and having a section thereof adapted to isolate one end of the pool from the other, said isolated section being of a variable depth.

Another object is to provide a swimming pool in accordance with the above objects which is of low-cost construction, easily installed, adapted for portability and yet large enough to permit swimming and diving by adults,

" wd States Patent ICC which is of rigid and sturdy construction and highly effective as a safe swimming facility.

These and other objects will become more fully apparent upon reference tothe following description.

In the drawings:

Fig. 1 is a plan view of the swimming pool constructed in accordance with the principles of this invention.

Fig. 2 is a longitudinal section taken in elevation along line 2-2 of Fig. 1. i

Fig. 3 is a transverse section taken in elevation along a plane indicated by line 3-"3 of Fig. 2.

Fig. 4 is a somewhat enlarged fragmentary top plan view of the swimming pool shown in Fig. 1.

Fig. 5 is a somewhat enlarged fragmentary section taken in elevation through a side wall of the swimming pool.

Fig. 6 is a somewhat enlarged fragmentary plan view of a corner of the pool showing portions thereof in cross section for illustrative convenience.

Fig. 7 is a somewhat enlarged fragmentary section showing the mechanism for holding an intermediate frame of the invention in upright position.

Fig. 8 is a slightly enlarged fragmentary section taken through the shallow end of the pool and showing the intermediate frame in a different position than that shown in Fig. 7.

Fig. 9 is a view similar to Fig. 8 and shows the intermediate frame in still another position of operation.

Fig. l() is a somewhat enlarged detail view of the j mechanism for controlling the position of the intermediate frame, as seen in Figs. 7-9, and shows such mechanismholding the intermediate frame in a substantial I horizontal position.

Fig. l1 is a fragmentary section taken on line 11-11 of Fig. 7.

Fig. 12 is a fragmentary section taken on line 12--12 u A swimming pool 10 of substantially rectangular shape i is illustrated in Figs. l and 2 containing a pool of water 11. Although the present invention is shown in connection with a swimming pool of rectangular shape, it is adaptable to circular, irregular or other shapes, as desired.

The pool 10 provides a tank V15 preferably made of sheet metal having a bottom wall 16 and opposed side and end walls 17, 18 respectively, upstanding from the bottom Wall.` The end or side walls may include glass panels fitted to the metallic portions thereof by means of packing or sealing members. The bottom wall is on several levels thus providing a lower substantially horizontally disposed deep end portion 19, an upwardly sloping portion 20 and an upper substantially horizontally disposed shallow-end portion 21. Constructed in this manner, the pool provides a deep-end 22 defined by the end and side walls adjacent to the deep-end portion 19` and sloping portion 20 of the bottom wall and a shallow-end 23 defined by the side and end walls adjacent to the shallow-end portion 21 of the `bottom wall. The tank provides an upper flanged ledge or walk 24 outwardly extended from the upper edges of the side and end walls. Such ledge may be covered with rubber matting or roughened, neither of which is shown in detail, to facilitate walking thereon without slipping.

As seen in Fig. 2, the tank 1S is preferably set in the ground, indicated at 30 with the shallow-end portion 214 of the bottom wall 16 rested on the surface 31 of the ground. Ladders, as 32, are provided for climbing up to `the ledge 24 thereby facilitating entrance to the pool.

These ladders may be adapted for releasable pivotal con Patented Mar. '11, 195sy nectcd, as indicated at, tothe tank. A diving board construction 34 is mounted adjacent to the deep end 22 of the pool and may be supported against the tank or independently thereof.

Inasmuch as safety is of utmost importance, installation of the tank in the above described manner is to be pre fet-red. In this way protection is afforded by the side and end walls protruding from the ground against persons accidentally falling into the pool. Ladders 32 may be removed when the pool is not in use. It is to be understood, however, that the tank is also adapted to be set into the ground with ledge 24 rested on the surface, or closely adjacent thereto, or with the deep-end portion 19 rested on the surface and shallow-end portion 21 supported in spaced relation to the surface.

Elongated hollow sleeves are secured, as by welding, to the end walls 18 adjacent to the ledge 24 and similarly constructed sleeves 4 1 are likewise secured to side walls 17 adjacent to the ledge. Brackets 42 join the adjacent ends of sleeves 40 and 41 at the corners of the tank 15. Pairs of closely spaced roller bearings 43 are mounted in longitudinal spaced relation within end sleeves 40 with a single roller bearing at each end thereof, as best seen in Figs. 4 and 6. Rods 44 are iitted in the roller bearings for rotation relative to the sleeve and are provided with bevel gears 45 on opposite ends thereof. The sleeves are provided with openings 46 downwardly directed toward the bottom wall 16 of the tank and longitudinally spaced along the sleeve. It will be noted that the openings are in individual registry with the space, indicated at 47, between the pairs of roller bearings.

Sleeves 41 are also provided with pairs of spaced roller bearings 50, rods 51 journalled therein and openings 52 inregistration with spaces 53 between the bearings. Only one end of the rods 51, however, have bevel gears 54 thereon. The adjacent bevel gears 45 and 54 at the corners of the tank 15 are in intermeshing engagement and crank handles 55 and 56, mounted in suitable bearings in the side wall 17 of the tank, are connected to end rods 44 for manipulation exteriorly of the tank. Each handle has a ratchet mechanism 57 associated therewith for locking the handle against rotation in one direction when engaged therewith.

Referring to the deep end 22 of the pool there is noted a substantially rectangular end frame 60 fitted to the deepend portion v19 of the 'bottom wall. Stretched across the frame is a foraminous screen member 61, conveniently of ne wire mesh interlaced for strength and to achieve substantial rigidity. The frame is mounted in the tank 15 for elevational or vertical movement between a position rested on deep-end portion 19 and a position above the surface of the water 11 in the pool, or otherwise stated, adjacent to the upper edge of the tank. For this purpose, cables 62 are connected to the frame at one end, threaded through the appropriate openingsv 46, 52 thereabove in the sleeves 40 and 41 and connectedat the other end to rods 44v and 51 in spaces 47 and 53-between` roller bearings 47, 53 respectively. The sleeves, rods, handles and cables form a convenient Windlass for raising or lowering the frame Aand foraminousmember in the tank. The frame, foraminous member and cables are preferably treated, as bypainting, with some suitable non-corrosive composition.

A similar'endframe 65 and foraminous member 66 is fitted to the shallow-end portion 21 of the bottom wall 16 and is adapted for elevational movement on cables 67 connected at opposite ends tothe frame and rods 44 and 51 in the same manner described in relation to cables 62.

An intermediate frame 70 of vsubstantially rectangular shape and provided with a foraminous member 71 is pivotally attached by straps 72 to the shallow-end frame for swinging movement between a position rested on the sloped portion 20 of the bottom wall 16, as seen in Fig. 9, and an upright position substantially perpendicular to the end frame 65. A pin 73 isextended laterally from each side of the frame substantially-centrally located on the frame. The side of frame 70 adjacent to the deep end 22 of the pool has a pair of extension brackets 75 adapted to rest on the adjacent side of frame 60 when all of said frames are in horizontal alignment.

A pair of arms are pivoted individually on pins 8l at each side of end frame 65 and are adapted for pivotal movement endwardly of the frame toward the deep end 22 of the pool. They are limited in downward pivotal movement by stops 82 extended outwardly from the frame 65. Each arm has a plurality of spaced notches 83 in longitudinal spaced relation therealong with one of the notches 84 adjacent to the end of the arm having a right angular hook therein.

Operation The operation of this invention is believed to be readily apparent and is briefly summarized at this point.

When it is desired to use the swimming pool 10 for swimming purposes or to clean it out, the crank handles S5 and 56 are rotated free of the ratchets 57 and the frames 60 and 65 lowered in to positions of rest in their respective end portions 19 and 21 of the pool. This is shown in Fig. 2. Assuming that the full pool is to be used in the usual manner, the intermediate frame 70 is rested on the sloping portion 20 as shown in Fig. 9, and the arms 80 rested on stops 82 extended toward the deepend 22 of the pool. Although not shown in the interests of drafting convenience, the shallow end 23 of the pool may ce made long enough to permit pivoting of the arms 80 toward the shallow-end and rested on bottom wall portions 21. The pool is thus in condition for unobstructed swimming throughout the full length and width thereof. lt is to be note-d that the foraminous members 61, @Sand 71 act as friction mats or floors to prevent slippage while Walking in the pool and especially down the sloping portion 2i).

ln the event that it is desired to vary the depth of the pool so as to extend the depth of shallow end 23 the entire length of the pool, the intermediate frame 70 is pivoted into horizontal position, as shown in Fig. 8, and the notches 84 in arms 80 engaged with pins '73 on the intermediate frame. The handle 55 is then rotated to wind cables 62 around rods 44 and 51 and thus to elevate end frame 60 until it engages brackets 75 in the intermediate frame. The ratchet 57 holds the deep-end frame in this elevated position. It Will be evident that the pool now is of uniform depth throughout corresponding to the normal depth of the shallow end, and may even be made more shallow by turning handles 55 and 56 further in the same direction as before. Similar adjustments at lower levels may of course be made with the deep-end frame 60 independent of the intermediate and shallow-end frames 7l) and 65, respectively.

With the deep-end frame 69 rested on the bottom wall portion 19 as initially described, the shallow-end 23 may be isolated from the deep-end 22 to prevent children, or those unable to swim, from intentionally or accidentally going into deepwater. For this purpose, the intermediate frarne 70 is pivoted into upright position, as shown in Fig. 7, and the innermost notches 83 on arms 3% engaged over pins 73 on such frame. This locks the intermediate frame in transverse position across the tank 15 with the foraminous member 71 forming a partition substantially parallel to the end walls 1S. In this posia tion, crank handle 56 may be rotated to elevate both end frame 65 and the intermediate frame 70 to any desired level and may be locked at such level by ratchet 57. Therefore, the shallow-end of the pool is not only isolated from the rest of the pool but the depth of the available swimming area may be changed to snit various individ uals. Children may beplaced in the isolated shallowend thus provided and others may swim at their leisure in the deep-end without constantly cautioning those unable to swim against Vwandering out of shallow water.

A stillV further use` of the frame. members is that of forming a cover over the pool when the pool is not in use. When such is desired, the crank handles 55, 56 are rotated and the frames 60, 65 elevated to a position adjacent to the upper edge of the tank and locked in this position by ratchets 57. During this operation, the 'intermediate frame 70 is held in either its upright position, as shown in Figs. 2 and 7 or in one of the other positions above or in horizontal alignment with frame 65. This is done to enable tting brackets 75 over the side of frame 60, adjacent to the intermediate frame, thus placing all of the frames in horizontal alignment, much as described above in relation to making the pool a uniform depth. Thus the foraminous members 61, 66 and '71 form a cover over the pool to prevent individuals from accidentally falling into the pool, to keep leaves and other debris from falling into the pool and by the appropriate use of padlocks locking intermediate frame to the deep-end frame and locking the handles against rotation to prevent unauthorized use of the pool.

It should be apparent from the foregoing that a highly adaptable arrangement has been provided for use in swimming pools. Although described in relation to a pool having a specific shape it is to be understood that the teachings of this invention include the use of a screen, net or other foraminous member, either in several sections, as described herein, or in one section to cover the entire pool and for use in a variety of shapes of pools having regular or irregular contours and with sloping, uniform or multi-level bottoms.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom withinthe scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a swimming pool provided with a bottom and having a shallow section and a deep section; frame members mounted for elevational movement in the deep and shallow sections of the pool; each frame member having a oraminous sheet mounted therein; the frame member in the shallow section of the pool including a iloor, and a partition pivotally connected to the iloor for movement between a substantially upright position in the pool and a position rested on the bottom of the pool; means for holding the partition in a plurality of angular positions relative to the iloor; means for releasably connecting the partition to the frame member in the deep section of the pool; and means connected to the frame member for adjusting the elevational positions thereof in the pool.

2. A partitioning apparatus for pools comprising a frame mounted in the pool for elevational movement therein, a foraminous member mounted within the frame, the frame having an end section and an inwardly extended section pivotally connected to the end section-for angular movement relative thereto, means for locking the inwardly extended section in any of a'plurality of angular positions relative to the end section including a position perpendicular thereto, a position oppositely obtusely angularly related thereto, and a position coplanar therewith, and means connected to the frame for elevationally positioning the frame in the pool.

3. A swimming pool adapted to hold a quantity of water having opposite ends, a bottom wall and side walls upstanding from the bottom wall, a pair of spaced substantially horizontally disposed frames positioned in each end of the pool adapted for elevational movement between a submersed position rested on the bottom of the pool and a position above the surface of the water, means mounted on the pool and connected to the frames for imparting said elevational movement to the frames,

, means for locking the frames in -a plurality of selected positions, an intermediate frame pivotally connected to one of the end frames for angular movement relative thereto between an upstanding position and a position rested on the bottom of the pool, means for locking the intermediate frame in a plurality of said angular positions including a position wherein the intermediate frame and said one end frame are substantially coplanar, the intermediate frame having a length at least substantially equal to the distance between said end frames, interengaging means on the intermediate and the other end frame for locking said frames together when in horizontal alignment, and a foraminous member supported in each of the frames.

4. A swimming pool adapted for safe use comprising a tank adapted to hold a quantity of water having a bottom wall and opposite end and side walls upstanding from the bottom wall, a pair of longitudinally spaced substantially horizontally disposed frames positioned in each end of the pool adapted for elevational movement between a submersed position rested on the bottom of the pool and a position above the surface of the water, hoist- `ing cables connected to the frames, windlass means mounted on the pool and connected to the hoisting cables forimparting said elevational movement to the frames, means for locking the windlass in -a plurality of selected positions, an intermediate frame pivotally connected to one of the end frames for angular movement relative thereto between an upstanding position substantially parallel to the end walls and a position rested on the bottom of the pool, means for locking the intermediate frame in a plurality of said angular positions including a position wherein the :intermediate frame and said one end frame are substantially coplanar, the intermediate frame having a length substantially equal to the distance between said end frames, interengaging means on the intermediate and the other end frame for locking said frames together when in horizontal alignment, and a foraminous member supported in each of the frames.

5. A swimming pool adapted to contain a quantity of water, comprising a bottom wall providing substantially horizontal end portions at different elevations forming deep and shallow ends interconnected by a sloping portion, upstanding walls integrally connected to the bottom wall enclosing the pool, a pair of substantially horizontally disposed end frames mounted in spaced relation at the deep and shallow ends of the pool, in juxtaposition to the upstanding walls adjacent thereto for elevational movement between positions above the water level in the pool and positions rested on their respective end portions of the bottom wall, an intermediate frame connected to lthe end frame at the shallow end of the pool extended between the upstanding walls for pivotal movement hetween an upstanding position at substantially right angles to the end frame connected thereto and a position rested on the sloping portion of the bottom wall, a foraminous 4screen supported in each of the frames, means for controlling the vertical position of the end frames in the pool, means for locking the intermediate frame in said upstanding position, and means for locking the intermediate `frame to the end frame at the deep end of the pool when all of said frames are in substantially horizontal position.

6. A swimming pool adapted to contain a quantity of water, comprising a bottom wall providing substantially horizontal end portions at diierent elevations forming deep and shallow ends interconnected by a sloping por- "in juxtaposition to the upstanding walls adjacent thereto for elevational movement between positions above the water level in the pool and positions rested on their respective ends portions -of the bottom wall, an intermediate rigid `foi'a'minous member connected to the rigid foraininous member at the shallow end of the pool extended between the opstanding walls for pivotal move ment between an upstanding position at substantially right angles to the end frame connected thereto and a position rested on the sloping portion of the bottom wall, windlass means mounted on the upstanding walls and connected to the foraminous members at each end of the pool for individually controlling the elevational position thereof, and arms pivotally connected to the {oraminous member at the shallow end of the pool for pivotal movement endwardly thereof at each side of the intermediate foraminous member and engageable therewith to lock such member in a plurality of selected positions including said upstanding position and a position in coplanar relation with the farominous member at the shallow end of the pool.

7. A swimming pool comprising a metallic tank having a pair of end walls, a pair of side walls and a bottom wall; the end and side walls providing an upper edge around the periphery of the pool and being joined to form corners of the pool; a ledge connected to the tank and outwardly extended in circumscribing relation to the upper edge thereof; the bottom wall providing horizontal floor portions at opposite ends of the tank disposed in elevationally spaced planes deiining deep and shallow sections of the pool and a sloping 'floor portion intermediate the horizontal portions; the tank being adapted for placement in the ground with the horizontal door portion associated with the shallow end of the pool rested on the surface of the ground; a pair of elongated tubular sleeves individually mounted on each side wall adjacent to the upper edges thereof; an elongated tubular sleeve individually mounted on each end wall adjacent to the upper edge thereof; each sleeve having a plurality of longitudinally spaced openings therein facing inwardly of the tank; pairs of spaced bearings mounted within the sleeves; rods individually journaled in the bearings of each sleeve; each rod having an end extended adjacent to a corner of the tank provided with a bevel gear intermeshing with a corresponding bevel gear on the rod adjacent thereto; crank handles connected to the rods for controlling rotation thereof; ratchet means mounted on the tank engageable with the handles for selecting and locking the handles against rotation; a pair of substantially rectangular end frames fitted respectively to the floor portions and end and side walls in the deep and shallow sections of the tank and adapted for individual elevational posi tioning within the tank between said door portions and edges of the tank thereabove; a rigid wire mesh mounted in each frame; a plurality of cables having extended ends connected to the frames and opposite vends individually extended through corresponding spaced openings in the sleeves on the side and end walls adjacent to the deep and shallow sections respectively and connected to the rods associated therewith intermediate pairs of spaced bearings therefor; a substantially rectangular intermediate frame pivotally connected to the end frame in the shallow section for movement between an upright position in the tank substantially perpendicular to said shailow section frame and a position lying flatly against the sloping floor; a rigid wire mesh mounted in the intermediate frame; the length of the intermediate frame being substantially equal to the horizontal distance between said shallow and deep section frames; pins outwardly extended from each side of the intermediate frame; a pair of arms pivotally connected to the shallow section frame at points inwardly spaced thereon from the pivotal connection of thevinterrnediate frame and having a plurality of notches therein selectively engageable with the pins on the inter mediate frame to lock such frame in a plurality of selected angular positions relative to the shallow section frame; stop members laterally extended from the shallow section frame adapted to abut against said arms to limit pivotal movement thereof to positions endwardly extended in substantially coplanar relation from the shallow section; the outermost notch in each arm having a hooked portion adapted in the coplanar position of each arm to receive the pin on the intermediate frame to lock such frame in a position endwardly extended from the shallow section frame and in substantially coplanar relation therewith; and brackets extended from the intermediate frame on the side thereof adjacent to the end frame in the deep section releasably engageable with such end frame when all of said frames are in substantially horizontal alignment.

S. In a swimming pool having a bottom wall, upstanding side walls, and opposite ends and being adapted to hold water for swimming purposes, a partitioning apparatus comprising a substantially rectangular open frame transversely extended between the side walls of the pool at a position intermediate the ends of the pool, a foramiuous member mounted in the frame, means connected to the frame pivotally mounting the frame iu the pool for pivotal movement between a position lying on the bottom wall of the pool and a position upwardly extended transversely of the pool above the water therein to divide the pool into two swimming areas, and means for locking the frame in said upwardly extended position.

9. A partitioning apparatus for pools comprising a frame mounted in the pool for elevational movement therein, a foraminous member mounted within the frame, the frame including a pair of sections pivotally interconnected for relative movement around a substantially horizontal axis, means for locking the sections in any of a plurality of angular positions relative to each other in cluding a position wherein the sections are substantially perpendicular to each other, a position wherein the sections are substantially oppositely obtusely angularly related to each other, and a position wherein the sections are tcoplanar, and means connected to the frame for elevationally positioning the frame in the pool.

l0. A swimming pool adapted to hold a quantity of water having opposite ends, a bottom wall and side walls upstanding fromthe bottom wall, a pair of substantially horizontally disposed frames positioned in each end of the pool adapted for elevational movement between a submersed position rested on the bottom of the pool and a position above the surface of the water, means mounted on the pool and connected to the frames for individually imparting said elevational movement to the frames, means for locking the frames in a plurality of selected positions, means on one of the frames adapted to engage the other frame for releasable interconnection o the frames, and a foraminous member supported in each of the frames.

11. In a swimming pool having a bottom wall, upstanding side Walls, and being adapted to hold water for swimming purposes, a partitioning apparatus comprising an open frame transversely extended between the side Walls o'f the pool, a foraminous member mounted in the frame, means mounting the frame in the pool for rnovement between a position upwardly extended transversely of the pool to divide the pool into two swimming areas and a position retracted therefrom, and means for locking the' frame in said upwardly extended position.

l2. In a swimming pool comprising a tank having an upper end edge, opposite side edges extended from the end edge, and an open cavity adapted to contain a quantity of water; end and side rods journaled for rotation along the end and side edges of the tank; means interconnecting the rods for unitary rotation; end and side cables suspended from the end and side rods adapted to be wound on and unwound from the rods; power means connected to one of the rods for imparting rotation to the rods; a frame having end and side edges connected to the end and side cables, respectively; and a body support member mounted in the frame adapted for elevational positioning in the tank upon rotation of the rods.

13. In a swimming pool having a bottom wall, opposite side walls upstanding from the bottom wall, and an end wall upstanding from the bottom wall and interconnecting the side walls, the side and end walls having upper edges, end and side bearings mounted on the end and side walls, respectively, adjacent to the upper edges, substan tially horizontal end an-d side rods rotatably journaled in the end and side bearings, respectively, and ,extended along the upper edges of the end and side walls, means on the rods interconnecting the rods for unitary rotation, means connected to one of the rods for imparting rotation thereto, a body supporting member having end and side peripheral portions, exible supports connected to the end and side rods for winding therearound incident to rotation of the rods in one direction and for unwinding therefrom incident to rotation in the opposite direction, the supports being extended downwardly into the pool and connected to the end and side peripheral portions of the body supporting member so as to support the body supporting member in a substantially horizontal position in the pool and whereby when the rods are rotated in said one direction the body supporting member is elevated and when the rods are rotated in said opposite direction the body supporting member is lowered, the body supporting member being maintained in a substantially horizontal position at all times by the rods and Hexi'ble supports.

References Cited in the le of this patent UNITED STATES PATENTS 1,091,909 Birmingham Mar. 31, 1914 1,101,166 Collins June 23. 1914 1,994,640 Giliasso Mar. 19, 1935 2,140,978 Beeby Dec. 20, 1938 

